The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.
With the availability and variety of fuels that exists, both now and into the future, it may be desirable for vehicles to have the capability of operating with more than one fuel type. In particular, it would be advantageous for a vehicle to be able to use of a variety of liquid and/or gaseous fuels, or mixtures of such fuels, depending on what fuel is available. This is particularly important in remote regions where fuel supply may be uncertain. Further, because of slow development of fuel distribution infrastructure in some regions, some vehicles need to use both gaseous and liquid fuels to overcome availability problems. In such circumstances, vehicle engines may need to run on combinations of gaseous and liquid fuels or mixtures of liquid fuels. Additionally, some engines may need to use two separate fuels at the same time.
Accordingly, there exist benefits in providing an engine which is capable of using more than one fuel type. It would also be desirable for any such engine to be configured to run on a combination of a gaseous fuel and a liquid fuel, and optionally also to run on either of the fuels separately.
There have been various proposals for delivery of two different fuels to an engine.
One such proposal is disclosed in US2002/0195088 which is directed to a dual fuel system for feeding a main fuel and a secondary fuel to an internal combustion engine. The dual fuel system utilises a common fuel injector configured for indirect fuel injection for delivery of fuel into an air intake duct of the engine. The common fuel injector is connected to two separate fuel paths, one for the main fuel and the other for the secondary fuel. Each fuel path has a separate fuel rail to which the common fuel injector is connected. The fuel injector has two separate fuel paths isolated from each other and each communicating with a respective fuel rail. As the fuel injector is configured to provide two separate fuel paths, the two fuels can be delivered in a common injection event. However, the two fuels are metered separately and delivered through separate delivery ports, albeit within the common fuel injector. Accordingly, the two fuels are neither delivered through the same delivery port nor brought together until delivery into the engine air intake duct; that is, there is no mixing of the two fuels when the engine is operating in a dual fuel mode until after delivery into the engine air intake duct.
The present invention, in at least one application thereof, seeks to provide the capability for an engine to use more than one fuel type, and to operate on either of the fuel types separately as well as operate on a combination of the two fuel types.
Any such engine would preferably also be configured to run on a combination of a gaseous fuel and a liquid fuel, and optionally also to run on either of the fuels separately.